In my games I'm still establishing the goals, even if I dangle multiple goals. I'm also applying external pressures and threats to move the game forward. The end result isn't quite a linear campaign because if they unexpectedly manage to kill a BBEG or thwart their plans, there isn't going to be a Deus Machina to keep the BBEG alive but it ends up following my high level fuzzy campaign outline the majority of the time.
That and I have a pretty episodic approach to my campaigns, when a group picks a direction I try to keep them more or less on the chosen path for a bit. There have been sessions where things go wildly sideways but those tend to be the exception to the rule, especially depending on the group.
Or maybe I'm running a sandbox campaign but we just have different definitions of what that means.